This invention relates to a method of operating a differential protection scheme, and to an electrical power network comprising a differential protection scheme.
Current differential protection schemes help to protect transmission lines within an electrical power system by identifying when a fault occurs in relation to the transmission lines. The basic principle of current differential protection is based on a calculation of a difference between the currents entering and leaving a protected zone. Tripping of a local circuit breaker is carried out when the difference exceeds a set trip threshold. In addition to tripping the local circuit breaker, a local terminal sends an intertrip signal to the remote terminals to ensure tripping at all ends of the protected zone.